Intelligent shortwave frequency management systems and associated methods

ABSTRACT

The present disclosure includes embodiments of a two-way wireless data communication system and associated methods. An embodiment of a system can include a network operations center (NOC), a plurality of fixed-location receive base stations (RBS) in communications with the NOC, and an intelligent shortwave communication network in communications with the NOC and the plurality of RBS and including a plurality of remote intelligent transceiver units (ITU). In an embodiment, for example, the NOC can be operative to a) compute rapidly a protocol under which nationwide communications is to be completed via coordinated operations of the linked ITU and RBS, b) determine propagating and clear electromagnetic wavelengths over an entire 3 MHz to 30 MHz shortwave band, and c) send a continuous stream of data indicating times and frequencies at which remote units can rapidly and efficiently transmit data and at which antenna sites can reliably and efficiently receive that data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and is a continuation of U.S.patent application Ser. No. 15/896,287, filed Feb. 14, 2018, titled“Intelligent Shortwave Frequency Management Systems and AssociatedMethods,” which is related to, and claims the benefit of, U.S.Provisional Application No. 62/458,962, filed Feb. 14, 2017, titled“Intelligent Shortwave Frequency Management Systems and AssociatedMethods,” all of which are incorporated herein by reference in theirentireties.

FIELD ON INVENTION

This invention relates generally to wireless communication systems andassociated methods and, in particular, to more efficient wide area datacommunications networks.

BACKGROUND

In today's world, unfortunately, existing and even certain proposedwireless communications network systems costing many millions of dollarshave failings of one type or another. Consider, for example, existingwireless wide area data networks which support communication between aremote or mobile field unit and a base station. These networks eitheruse terrestrial or satellite-deployed base stations. Terrestrial systemscan be further classified as either one-way or two-way. Some terrestrialand satellite systems that cost less allow remote users to receive databut provide poor or no capability for remote users to send data.Although some systems support two-way data transfer, these typicallyprovide only limited geographic coverage, which is related to thecoverage radius of their transmission towers. In addition, such networksalso typically exhibit relatively poor penetration of buildingstructures, due to the high carrier frequencies at which they operate.

Other existing and proposed two-way terrestrial commercial systemsinclude cellular networks and mobile data networks that, do not, bydesign, cover the entire continental United States. It is estimated thatover 40% of the United States does not have commercial wireless dataservice. Many remote privately owned assets are in these areas and needto be economically monitored. The data rates of these systems may bequite high, but each system requires the users to be within a closerange, generally 10 miles or less, of the system infrastructure. Thisinfrastructure is extremely expensive, requiring hundreds of millions ofdollars to build a nationwide network. It can sometimes be costeffective to build such infrastructure in areas of high populationdensity, and indeed, roughly 90% of the United States population can besupported by such systems. It is simply not economical for providers ofsuch services to install the required infrastructure in remote areas oflow population density, however. In addition, local infrastructure maybe subject to manmade or natural disasters.

Several satellite networks, both existing and proposed, have beendesigned to address the issue of poor geographic coverage. Thesesatellite-based systems typically require a tremendous investment ininfrastructure. The infrastructure is located in orbit where it cannotbe installed, maintained or replaced without large expenditures forspace-launch vehicles. In addition, the mobile subscriber devicesrequired to communicate with such systems are relatively expensive.Furthermore, the field devices need to be within the line of sight ofthe satellite, since they must typically have overt, high gainelectromagnetic reception devices such as dishes or long antennas. Suchsystems are thus impractical for certain applications.

An example is the problem faced by the manager of fleet vehicles. Theassets for which the manager is responsible are highly mobile, and theycan be located virtually anywhere. These assets are easily stolen andexpensive to insure, and such assets can also become unproductive whenit cannot be located or are out of communication ranges. Similarproblems exist in other industries as well. For example, there isincreasing pressure on the railroad industry to move towards scheduledservice, to facilitate just-in-time delivery in an effort to bettercompete with the trucking industry. To achieve this goal, the manager ofa railroad system would ideally be able to quickly determine thelocation of each and every rail car on a regular basis, no matter wherethe rail car is located. Optimum routing and delivery time may then beaccurately predicted.

In such applications, it would be advantageous to be able to query aremote device in order to determine its status and location, but withminimum cost. Current cellular mobile service costs are increasing asthe carriers move from 2G, 3G to 4G and 5G. In addition, higher datarates over limited capacity communications channels are increasingcongestion, and transmissions are lost. Increasingly, basicmachine-to-machine and emergency communications cell data services arebecoming unreliable and more expensive.

Other industries, such as the trucking and shipping industries, strugglewith the lack of the ability to track accurately and inexpensively thelocation of shipping containers no matter where they are located. Anyone shipping container may hold thousands or potentially millions ofdollars of valuable goods. Clearly, it would be advantageous to knowwhere they are at all times.

Similar demands are made in remote meter or sensor reading, facilitymonitoring, security, buoy monitoring, and other applications.Applicants have recognized that while some needs of such applicationcould be met by combining a position sensing device such as a GlobalPositioning System (GPS) receiver unit together with an existing two-waymobile data communication device such as a cellular or satellitetransceiver, the system would nevertheless exhibit the aforementioneddifficulties of high installation and operation cost, and be subject tothe inability to operate in anything but a region of direct line ofsight or close proximity to the system infrastructure.

SUMMARY

In view of the above, Applicants recognized a need for ubiquitous andmore reliable wireless communication networks, systems, and methods ofdata communications of various types. Accordingly, embodiments of radiocommunication systems and associated methods, which allow for moreefficient wide area data communications networks, such as by making useof a shortwave antenna sites for inbound links and a centralizedcontroller for coordinating use of available and clear electromagneticwaves, among other features, are provided.

The embodiments of wireless systems and associated methods describedherein are at least in part focused on needs for highly reliable two-waydata communications that takes the form of short messaging betweenautomated end points or user devices. Such systems are able to providecommunication without local infrastructure over a wide geographicinternational area. Some of the systems, methods, and operationalconcepts described in U.S. Pat. Nos. 5,765,112, 5,734,963 and 5,640,442may be utilized in the systems and methods described in the presentdisclosure. Embodiments of the systems and methods of the presentdisclosure overcome operational barriers that were not previouslyanticipated, as well as introduce additional layers of capability. Thetwo-way wireless data communications system described herein efficientlyprovides ubiquitous connectivity through intelligent shortwave frequencymanagement (ISFM). The physical configuration and basic operation ofthis shortwave communication system are described in U.S. Pat. Nos.5,765,112 and 5,640,442.

The present disclosure also provides embodiments of a controllingnetwork infrastructure that rapidly and virtually instantaneously givesinstructions to, and requests data from, not only many remote fieldunits distributed across the U.S., but also a linked network ofdistributed fixed antenna sites, to maximize the efficient use ofchannels in the 3 MHz to 30 MHz band. Shortwave transmissions, which arereflected back to the earth by the ionosphere, cover thousands of mileswith no intermediate infrastructure. Thus, embodiments of the systemsand methods described could be used worldwide.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing aspects, features, and advantages of the presentdisclosure will be further appreciated when considered with reference tothe following description of embodiments and accompanying drawings. Indescribing the embodiments of the disclosure illustrated in the appendeddrawings, specific terminology will be used for the sake of clarity.However, the disclosure is not intended to be limited to the specificterms used, and it is to be understood that each specific term includesequivalents that operate in a similar manner to accomplish a similarpurpose.

FIG. 1 is a block diagram of a two-way shortwave radio communicationnetwork, in accordance with example embodiments of the disclosure.

FIG. 2 illustrates typical locations for fixed receive sites across theUnited States, in accordance with example embodiments of the disclosure.

FIG. 3 illustrates a normal profile of propagating channels that an ISFMprotocol uses to select optimum channels for immediate communications,in accordance with example embodiments of the disclosure.

FIG. 4 illustrates results of a clear frequency analysis, in whichunused shortwave channels are isolated for further analysis andpotential issuance as remote initiated frequencies (RIF) to remote units(ITU), in accordance with example embodiments of the disclosure.

FIG. 5 illustrates a process by which a noise floor calculation is made,and by which the quietest channels are issued to remote units, inaccordance with example embodiments of the disclosure.

FIG. 6 illustrates a process used in prior art to allocate, assign andissue operating frequencies to remote units.

FIG. 7 illustrates an improved frequency allocation process that allowsmore frequencies to be issued from a reserve pool in any given intervalof time, in accordance with example embodiments of the disclosure.

FIG. 8 is a detailed flowchart that illustrates the efficient issuance,monitoring, and ultimate success rate of the intelligent frequencyallocation process, in accordance with example embodiments of thedisclosure.

FIG. 9 is a map of the continental United States illustrating how it ispartitioned when RIF are managed to allow simultaneous frequencyutilization, in which two or more messages are sent over the sameshortwave channel in the same time slot, in accordance with exampleembodiments of the disclosure.

FIG. 10 illustrates how receive site antenna array beam directivity isused to simultaneous send two or more messages over the same shortwavechannel in the same time slot, in accordance with example embodiments ofthe disclosure.

DETAILED DESCRIPTION

The foregoing aspects, features, and advantages of the presentdisclosure will be further appreciated when considered with reference tothe following description of embodiments and accompanying drawings. Indescribing the embodiments of the disclosure illustrated in the appendeddrawings, specific terminology will be used for the sake of clarity.However, the disclosure is not intended to be limited to the specificterms used, and it is to be understood that each specific term includesequivalents that operate in a similar manner to accomplish a similarpurpose.

When introducing elements of various embodiments of the presentdisclosure, the articles “a”, “an”, “the”, and “said” are intended tomean that there are one or more of the elements. The terms “comprising”,“including”, and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. Anyexamples of operating parameters and/or environmental conditions are notexclusive of other parameters/conditions of the disclosed embodiments.Additionally, it should be understood that references to “oneembodiment”, “an embodiment”, “certain embodiments”, or “otherembodiments” of the present disclosure are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Furthermore, reference to termssuch as “above”, “below”, “upper”, “lower”, “side”, “front”, “back”, orother terms regarding orientation or direction are made with referenceto the illustrated embodiments and are not intended to be limiting orexclude other orientations or directions.

ISFM systems and associated methods as described in the presentdisclosure improve previous processes in the field such that morecommunication channels can be made available and greater quantities ofdata can be sent over fixed capacity allocations granted under FederalCommunications Commission (FCC) shortwave licenses. The presentprocesses also can correct inefficiencies and delays in the frequencyutilization process, not just from a FCC compliance standpoint, but alsofrom the standpoint of reducing the probability of another usertransmitting on the same channel. Additionally, it defines a variety ofways that intelligently crafted operations and message structures canmake optimum use of the bandwidth, time slots and power allocationsgranted by the FCC.

In various embodiments of the present disclosure, a two-waycommunication system includes a plurality of base stations, a networkoperations system, and one or more remote transceiver units. Each of theplurality of base stations is operable to scan a plurality offrequencies in a 3 Megahertz to 30 Megahertz frequency band to determinepower and noise floor levels for each of the plurality of frequencies,determine whether a frequency of the plurality of frequencies meets aclear frequency criteria based on the power and noise floor levels ofthe frequency during at least two consecutive scans, determine whetherthe frequency meets a volatility criteria based on the power and noisefloor levels of the frequency during multiple scans conducted within atime duration, and generate a set of frequencies that meet the clearfrequency criteria and the volatility criteria. The network operationssystem is operable to coordinate the scanning of frequencies at theplurality of base stations, receive the sets of frequencies from theplurality of base stations, generate a list of frequencies available fortransmitting data thereon from the sets of frequencies, and transmit thelist of frequencies. The one or more remote transceiver unit is operableto receive the list of frequencies from the network operations system,select a frequency from the list of frequencies, and transmit data onthe selected frequency. The list of frequencies may include times andfrequencies at which the remote transceiver units can optimally transmitdata and at which receive base stations can receive the data. In someembodiments, the plurality of scanned frequencies is a portion of aplurality of sampling frequencies in a 3 Megahertz to 30 Megahertzfrequency band and the network operations system transmits the list offrequencies to the remote transceiver unit prior to all of the samplingfrequencies being scanned and analyzed to reduce delay between analyzinga frequency and issuing the frequency for use. In some embodiments, thenetwork operations system is operable to determine one or morefrequencies on the list of frequencies not used by the remote receiverunits within a time window and reissue the one or more frequencies tothe remote receiver units.

A shortwave communication network is in communication with the networkoperations system and the plurality of receive base stations and the oneor more remote transceiver units. The network operations system isoperative to compute a protocol under which nationwide communications isto be completed via coordinated operations of at least one receive basestation and at least one remote transceiver unit, determine a list offrequencies within at least portion of a 3 Megahertz to 30 Megahertzfrequency band that meet a clear frequency criteria and a volatilitycriteria based on power and noise floor levels detected through aplurality of consecutive frequency scans, and transmit data packets tothe remote transceiver units indicating times and frequencies at whichthe remote transceiver units can transmit data and at which receive basestations can receive the data. In some embodiments, each of the remotetransceiver units records a time of arrival of a transmission from thenetwork operations system and transmits the time of arrival to thenetwork operations system to enable the network operations system todetermine the approximate geo-location of each remote transceiver units.In some embodiments, all or a subset of the remote transceiver units aregrouped together into a group based on geo-location, classification,function, or any combination thereof, and same or similar instructionsare sent to all the remote transceiver units in the group.

In various embodiments, a method of configuring communications includesa) coordinating, at a network operations systems, scans of a pluralityof frequencies in a 3 Megahertz to 30 Megahertz frequency band to beconducted at a plurality of receive base stations communicative with thenetwork operations systems, b) scanning, at the plurality of receivebase stations, the plurality of frequencies to determine power and noisefloor levels for each of the plurality of frequencies, c) determiningwhether a frequency of the plurality of frequencies meets a clearfrequency criteria based on the power and noise floor levels of thefrequency during two consecutive scans, d) determining whether thefrequency meets a volatility criteria based on the power and noise floorlevels of the frequency during multiple scans conducted within a timeduration, e) generating a list of frequencies that meet the clearfrequency criteria and the volatility criteria, and f) transmitting thelist of frequencies to one or more remote transceiver units.

In some embodiments, the method may further include removing, by eachreceive base stations, unauthorized or skipped frequencies from furtheranalysis. In some embodiments, the method may further includedistributing the list of frequencies into a plurality of data packetsand transmitting the plurality of data packets as a continuous datastream. The plurality of scanned frequencies may be a a portion of aplurality of sampling frequencies in a 3 Megahertz to 30 Megahertzfrequency band and the list of frequencies is transmitted prior to allof the sampling frequencies being scanned and analyzed. The method mayfurther include determining one or more frequencies on the list offrequencies not used by the one or more remote receiver units andreissuing the one or more frequencies to the one or more remote receiverunits. The method may also further include selecting, by at least one ofthe one or more remote receiver units, a selected frequency from thelist of frequencies and transmitting a message in a message data packeton the selected frequency, the message data packet having one of aplurality of data sizes, the plurality of data sizes incrementing by sixbytes.

In some embodiments, determining whether the frequency meets thevolatility criteria may include scanning the frequency a plurality oftimes during the time duration, determining the power level and noisefloor level of the frequency for each scan, designating the frequency asclear or not clear for each scan based on whether the power level ishigher than the noise floor level for the respective scan, determining anumber of times the frequency changes between being clear and not clearduring two consecutive scans of the plurality of scans, and determiningwhether the frequency meets the volatility criteria based on whether thenumber of times is higher than a threshold number.

The figures and descriptions presented below provide examples of variousembodiments of the present application. FIG. 1 is a block diagram of atwo-way shortwave radio communication network 100, in accordance withexample embodiments of the disclosure. In one or more embodiments,remote units 106, or remote assets, communicate over a shortwave link toa network operations center (NOC) 102 via one or more remote basestations (RBS) 104. FIG. 2 illustrates typical locations for fixedreceive sites 204 across the United States, in accordance with exampleembodiments of the disclosure. To efficiently use the assigned spectrum,the system defines shortwave frequency channels that not only propagateas shown in FIG. 3, but also have been declared clear by an occupancyassessment technique. FIG. 3 illustrates a normal profile 300 ofpropagating channels 308 that an ISFM protocol or process uses to selectoptimum channels for immediate communications, in accordance withexample embodiments of the disclosure.

Receivers 110 at each RBS 104 site scan the 3 MHz to 30 MHz band, andsend the information to the frequency analysis processor (FAP) 112,which evaluates those channels and chooses the ones with no discernibletransmissions/receptions and thereby declares them as clear channels.Upon receiving clear channel data from the RBS sites 104, a propagationanalysis processor (PAP) 114 analyzes clear channels against allocatedbands, propagation probabilities and a sectored coverage map, and issuesan optimized frequency list to be used for transmissions by remoteassets. The method of performing assessment of clear channels can bebroken up into the following major steps of frequency scanning, noisefloor calculation, clear frequency assessment, and exclusion of volatilefrequencies. Each of these steps is described further below.

Each RBS 104 FAP 112 is equipped with one or more receivers 110 capableof scanning the shortwave spectrum from 3 to 30 MHz within a fewseconds, collecting the frequency and radio frequency power level inpre-determined bins. The scan at each RBS 104 is timed and coordinatedby the NOC 102. In addition, the FAP 112 at each RBS 104 automaticallyremoves unauthorized or skipped frequency bands from any furtheranalysis by the FAP 112. An embodiment of this process 400 isillustrated in FIG. 4, in which clear frequencies 416 are selected fromscanning a range of assigned frequencies 418.

Referring to FIG. 5, which illustrates calculation of noise floor, whencalculating the noise floor 520 for a given frequency 522, the currentpower level is defined as the median of the current scanned power leveland the two previously collected scan levels. The result can be used asan example of an evaluation algorithm that favors leaving an apparentoccupied channel in a previous state for at least one scan in order todetermine if the variation was anomalous. Using newly derived currentpower levels for each group of frequencies, the FAP 112 establishes aconservative noise floor 520 by measuring noise power levels 45 kHz toeither side of the subject frequency, computing an interim noise floorfor the selected frequency by taking median power levels of it and thesurrounding frequencies, then adding 5 dBm to the interim noise floor toestablish a conservative noise floor.

Given the above scanned power levels and computed noise floor for eachchannel, the derivation of clear frequencies becomes a simple comparisonof the scanned power and the noise floor. In one or more embodiments,the FAP 112 determines the clear state for each of the frequency groupsby determining if the scanned power level for the group is lower thanthe computed noise floor level. A channel is determined to be clear forthis scan if this condition is true. In one or more embodiments,however, being clear for one scan is not sufficient for the system todeclare the frequency clear for use. For a frequency bin 522 to bedeclared clear for remote asset use, the frequency must remain in aclear state for three consecutive scans of that frequency bin.

At the conclusion of the channel assessment sequence, the FAP 112 hasdeveloped a list of frequencies that have been clear for threeconsecutive scans and have met the volatility criteria. This list ofclear frequencies (called “remote initiated frequencies” or RIF) isforwarded to the NOC 102, which correlates data from multiple RBS sites104. The NOC 102 also may perform a propagation analysis and issue astream of clear and propagating frequencies over an outboundcommunications link.

An example of one of the goals of processes described in the presentdisclosure is to predict, as accurately as possible, that a clearfrequency will remain clear for at least as long as it takes to transmita message. In order to facilitate this goal, the volatility of eachfrequency is established. Volatility of a frequency is defined as anindex representing the number of transitions between clear and unclearfor each given scan relative to its previous scans. Volatility in thesystem is maintained on a frequency for a sliding one-minute window. Inone or more embodiments, if a frequency changes between clear and in-useor in-use and clear in excess of a pre-determined threshold within theone minute time window, then the frequency is considered to be toovolatile and is excluded from the clear frequency list sent to the NOC102.

The duration and efficiency of any proposed clear frequency scanningprocess is influenced by the activities and intervals that make up theoverall shortwave band evaluation process. FIG. 6 illustrates a timeline600 for the creation, distribution, reception, and use of a RIF whenused with a 4-second message under the previous techniques. Underprevious methods, as illustrated, the FAP 112 scanning process 624operated on a 5-second interval. That is, it took the FAP 112 about 5seconds to scan the assigned shortwave frequency band and record theresults. Then, in conjunction with the PAP 114 filtering anddistribution process, the FAP 112 would issue a new block of clear andpropagating frequencies every 10 seconds. The PAP 114 meters outfrequencies such that a continuous stream is available until the nextblock of clear frequencies arrives from the FAP 112. Once issued by thePAP 114, these RIFs traverse the internet and enter the outboundcommunication processor. The ITU 106 then receives the data, selects aRIF, tunes the antenna to a predetermined setting and broadcasts amessage. This clear-and-propagating frequency sampling process addssignificant delay (latency) to those frequencies that fall into theearly part of a scanning cycle. By the time data from the third scan ispackaged and sent to the NOC 102, the lowest frequencies could be over 8seconds old. The chance of another user interfering with transmissionsincreases with every second from the time the channel is evaluated untilthe time the message is completed. So it is advantageous to find a wayof reducing the overall delay.

FIG. 7 illustrates a process of clear frequency reporting 700 under thepresent disclosure, which provides an improved way to minimize delay,maximize the use of clear frequencies, and increase the RIF rate.Specifically, the process includes sending small packets 724 of clearfrequencies as they are observed, rather than waiting for the full bandto be scanned and evaluated. Thus, the time delay between scanning andsending of a clear frequency is reduced.

FIG. 8 is a flowchart 800 that illustrates the efficient issuance,monitoring, and ultimate success rate of the intelligent frequencyallocation process. Instead of collecting sampled frequencies in a5-second bin and shipping the entire packet as an integral unit,embodiments as described in this disclosure have clear channels gatheredin incremental buckets 826. For example, if 954 frequencies are scannedin 5 seconds, about 95 frequencies are sampled every half second. Ifthese are issued to the NOC 102 as they are gathered, the delay of theearliest sampled frequencies is reduced by 4.5 seconds. Thissignificantly reduces the probability of a collision with another user'stransmission.

As an additional advantage, for example, the incremental scanningscenario allows enough time for RIFs to be reissued, and frequencies tobe reused, within an allocated window. Thus, if the NOC 102 issues a RIFand receives no response on that RIF for more than 2.2 seconds, it meansthat the RIF was not used by any remote unit and therefore, because of a10 second utilization window, can instantly be reissued without waitingfor the results of a new scan. If an ITU 106 does not use this secondannouncement, the RIF can be used a third time. This process, inessence, increases the size of the RIF pool and allows a more continuousflow of RIFs during limited bandwidth times of the day, year, or sunspotcycle. This may be particularly advantageous if a system was heavilyloaded and the capacity needed to be increased.

Capacity could be further enhanced by polling unmanned or non-criticalunits within a small, predetermined window in time, or by allowing asignificant latency (e.g., a one-hour minimum) for non-critical units.In this improved operation, the 4-second message delivery time can beshortened, and the number of frequency reissuing cycles increased byraising the data rate and/or reducing the effective overhead load.

Under the system operating under previous techniques, all message sizesare defined by a pre-determined protocol that says they must be 12, 30,36, 48, and 60 bytes. There is nothing in between. If a message requiresonly 13 bytes, under the present message structure, a 30-byte packet issent which is only 54.2 percent efficient. In this example, 45% of thecapacity is wasted. Thus, it is apparent that significant capacity canbe lost by inefficient message formatting. Although there may beadvantages to have certain packet sizes, having these packet sizesincrease in smaller steps can save significant capacity. This isparticularly evident from the 12 and 30 byte examples. Under thetechniques of the present disclosure, particularly sizes in 6 byte or 4byte increments rather than the current 12 byte increments are utilized.

The reuse of RIFs adds an additional capacity advantage. In one or moreembodiments, the system accommodates the duplicate use of frequencies bymodifying PAP software, and increasing the number of receivers. FIG. 9is a map partitioned to illustrate an example of simultaneous frequencyutilization. As an example, referring to FIG. 9, for Operations in theUnited States, such a technique makes it feasible for the East Coast 928to simultaneously use the same frequencies as the West Coast 930, which,ideally, doubles the number of available channels for those two regions.Because the Midwest 932 needs its own set of RIFs, however, themultiplication factor is less than two, depending upon the algorithmused to select frequencies for reuse. A conceptual illustration of howthe reuse of RIFs might be implemented is shown below where thecontinental United States is divided into three principal sectors: onefor the East 928, one for the West 930, and another for the Midwest 932.

While frequency reuse can be applied on a region-by-region basis, asdiscussed above, another process for frequency reuse, for example, canbe implemented on a sector/beam/propagation basis. Specifically, thebeams and sectors can be used as the separator as opposed to the region.For example, as illustrated in FIG. 10, Massachusetts 1034 and Florida1036 can be used as separable regions just like East and West. In thisexample application, a given frequency is assigned to beams at the Texas1038, Minnesota 1040, and Colorado 1042 sites that point to the Floridasector 1036, while the same frequency is simultaneously assigned todifferent beams at the Texas 1038, Minnesota 1040, and Colorado 1042sites that point to the Massachusetts sector 1034. Thus, a similar setof RIFs are issued via the outbound link to both the Massachusettssector 1034 and the Florida sector 1036, while receivers on therespective RBS beams are tuned to correspond to the issued RIFs.

In one or more embodiments, whenever and wherever a channel ispropagating in the USA, a RIF is sent to any and all sectors, providingthere are enough receivers on enough beams to cover any message thatmight be returned by an ITU 106 from that sector and on that frequency.Wherever an RBS receiver/beam clearly picks up a message on thatfrequency, it is forwarded to the NOC 102, even if other RBS 104receivers/beams pick up other messages, whether from north-south oreast-west redundancies. Since the upgraded NOC 102 can distinguishbetween different same-time messages from different sectors and sources,the concept of frequency reuse is put to advantage. In addition, thefull disclosure of U.S. Pat. Nos. 5,765,112, 5,734,963 and 5,640,442 arehereby incorporated herein by reference in their entirety.

This application claims the benefit of, and is a continuation of U.S.patent application Ser. No. 15/896,287, filed Feb. 14, 2018, titled“Intelligent Shortwave Frequency Management Systems and AssociatedMethods,” which is related to, and claims the benefit of, U.S.Provisional Application No. 62/458,962, filed Feb. 14, 2017, titled“Intelligent Shortwave Frequency Management Systems and AssociatedMethods,” all of which are incorporated herein by reference in theirentireties.

The foregoing disclosure and description of the disclosed embodiments isillustrative and explanatory of the embodiments of the invention.Various changes in the details of the illustrated embodiments can bemade within the scope of the appended claims without departing from thetrue spirit of the disclosure. The embodiments of the present disclosureshould only be limited by the following claims and their legalequivalents.

1. A two-way wireless data communication system, the system comprising: a network operations system; a plurality of receive base stations in communications with the network operations system; and a shortwave communication network in communication with the network operations system and the plurality of receive base stations and including a plurality of remote transceiver units, the network operations system being operative to compute a protocol under which nationwide communications is to be completed via coordinated operations of at least one receive base station and at least one remote transceiver unit, determine a list of frequencies within at least portion of a 3 Megahertz to 30 Megahertz frequency band that meet a clear frequency criteria and a volatility criteria based on power and noise floor levels detected through a plurality of frequency scans during a selected time duration, and transmit data packets to the remote transceiver units indicating times and frequencies for the remote transceiver units to transmit data and the receive base stations to receive the data.
 2. The system of claim 1, wherein each of the plurality of remote transceiver units records a time of arrival of a transmission from the network operations system and transmits the time of arrival to the network operations system to enable the network operations system to determine the approximate geo-location of each remote transceiver units.
 3. The system of claim 2, wherein all or a subset of the plurality of remote transceiver units are grouped together into a group based on geo-location, classification, function, or any combination thereof, and same or similar instructions are sent to all the remote transceiver units in the group.
 4. The system of claim 3, wherein each of the plurality of receive base stations is operable to scan a plurality of frequencies in a 3 Megahertz to 30 Megahertz to determine power and noise floor levels for each of the plurality of frequencies.
 5. The system of claim 1, wherein each of the plurality of receive base stations is operable to determine whether a frequency of the plurality of frequencies meets the clear frequency criteria based on the power and noise floor levels of the frequency during at least two consecutive scans.
 6. The system of claim 5, wherein each of the plurality of receive base stations is operable to determine whether the frequency meets the volatility criteria based on the power and noise floor levels of the frequency during multiple scans conducted within a selected time duration.
 7. The system of claim 6, wherein times and frequencies for which the remote transceiver units are to transmit data and the receive base stations are to receive the data are transmitted as a continuous data stream to reduce delay between analyzing a frequency and issuing the frequency for use.
 8. The system of claim 1, wherein one or more frequencies on the list of frequencies not used by the one or more remote transceiver units within a time window are reissued to use by the network operations system.
 9. A computer-implemented method comprising: coordinating, at a network operations systems, scans of a plurality of frequencies in a 3 Megahertz to 30 Megahertz frequency band to be conducted at a plurality of receive base stations communicative with the network operations systems; scanning, at the plurality of receive base stations, the plurality of frequencies; determining, at the plurality of receive base stations, the power level and noise floor level of the frequency for each of a plurality of scans; determining whether a frequency of the plurality of frequencies meets a clear frequency criteria based on the power and noise floor levels of the frequency during two consecutive scans; determining whether the frequency meets a volatility criteria based on the power and noise floor levels of the frequency during multiple scans conducted within a selected time duration; generating a list of frequencies that meet the clear frequency criteria and the volatility criteria; and transmitting the list of frequencies to one or more remote transceiver units.
 10. The computer-implemented method of claim 9, further comprising: removing, by each receive base stations, unauthorized or skipped frequencies from further analysis.
 11. The computer-implemented method of claim 10, further comprising: scanning the frequency a plurality of times during the time duration; designating the frequency as clear or not clear for each scan based on whether the power level is higher than the noise floor level for the respective scan; determining a number of times the frequency changes between being clear and not clear during two consecutive scans of the plurality of scans; and determining whether the frequency meets the volatility criteria based on whether the number of times is higher than a threshold number.
 12. The computer-implemented method of claim 11, further comprising: distributing the list of frequencies into a plurality of data packets; and transmitting the plurality of data packets as a continuous data stream.
 13. The computer-implemented method of claim 9, wherein the plurality of scanned frequencies is a portion of a plurality of sampling frequencies in a 3 Megahertz to 30 Megahertz frequency band and the list of frequencies is transmitted prior to all of the sampling frequencies being scanned and analyzed.
 14. The computer-implemented method of claim 13, further comprising: determining one or more frequencies on the list of frequencies not used by the one or more remote receiver units; and reissuing the one or more frequencies to the one or more remote receiver units.
 15. The computer-implemented method of claim 14, further comprising: selecting, by at least one of the one or more remote receiver units, a selected frequency from the list of frequencies; and transmitting a message in a message data packet on the selected frequency, the message data packet having one of a plurality of data sizes, the plurality of data sizes incrementing by six bytes. 